At present we use Joomla for all our client websites.  We will be adding Wordpress soon. 
Both of these website systems allow the client to update their own websites as well as being based on a "template" system or in other 
words, a predesigned website structure/format that can then be customised to suit the client.

We will also adapt a current website to a Joomla (and soon Wordpress) one so that it can be edited by you as well as benefit from all the expansion possibilities that the abovementioned systems facilitate.

What is Joomla?

Joomla is a Content Management System (CMS) that gives you the client an editable interface to your website allowing you to update, edit and expand your website content.
It is based on a highly customisable 'template' system(see below) and has a large amount of 'extensions'(see below) that give you the capability to do just about anything you would want to do with a website.

Templates

There are a number of companies that make excellent templates for Joomla such as Joomla Bamboo, Rockettheme, Template Monster, Shape 5, Joomla Designs, Joomla Junkie to name a few.

Editing your Website

In the backend of Joomla you can edit and add any content

Extensions

There are large number of extensions available that can give your site just about any capability that you want